Phlegm or sputum as it is commonly referred to is a fluid of varying consistency that is secreted by the mucous glands and cells lining cavities. It is produced all of the time in the respiratory passages to keep the lining moist as it may quickly dry up with the movement of air. It is also useful in trapping dust and microbes in the air before it reaches deep in the body. Mucus is normally clear to slightly white in color but can change as a result of physiological alterations or diseases in the affected area.
Apart from changes in color, the quantity and viscosity (thickness) of the mucus can also change with certain diseases. Certain conditions will give rise to specific color changes in the mucus bur this is not always a reliable indication of the cause. Excessive mucus production is usually associated with inflammation but the cause of the inflammation can vary significantly, from infections to allergies and autoimmune diseases.
Clear to White Mucus
Although clear to white mucus is considered normal, most of the time it is never noticed. It is either swallowed or dries up and past out as crust which we often refer to as ‘boogers’. Excessive amounts of mucus that is clear to white may be seen with:
- Acute bronchitis which is an inflammation of the bronchi. It is usually due to an infection and often starts after a cold or the flu. Sometimes it can be viral but often it arises as a secondary bacterial infection. Sometimes it is due to irritation caused by inhaling toxic gases or other environmental toxins. The mucus can quickly turn to a yellow to brown color if left untreated.
- Asthma is a condition that also involves the bronchi where there is narrowing of the air passages due to swelling of the bronchi walls and excessive mucus production. It is usually associated with allergies and other allergic conditions like allergic rhinitis (hay fever) or atopic dermatitis (eczema). Wheezing is a characteristic symptom of asthma along with difficulty breathing.
- Gastroesophageal reflux disease (GERD) is another condition where clear to white mucus may be seen in excess. It arises with the backwards flow of stomach acid into the esophagus and sometimes rising as high as the throat and even the nose. The acid and enzymes causes inflammation and excessive mucus is produced as a result.
Orange, Pink to Red Mucus
Any sign of red in the mucus, be it a slightly orange (rust-colored), pink or a red hue should raise the concern about blood being present in the mucus. This is usually considered to be a serious sign as it may be indicative of some deadly infections. Foods and beverages with a strong orange, pink or red colorant can taint the mucus even though there is no blood present in the mucus.
- Pneumonia is an infection of the lung tissue that may present with bleeding seen as orange, pink or red mucus.There are many different organisms that can cause pneumonia but bacterial pneumonia is often more serious. Fungal pneumonia is rare and more commonly seen in immune compromised individuals. Pneumococcal pneumonia typically presents with rust-red mucus production.
- Pulmonary embolism is a condition where a blood clot blocks the major blood vessels to the lungs. It can lead to coughing up of large amounts of blood. It arises suddenly and is often related to a blood clot elsewhere in the body like in the leg with deep venous thrombosis (DVT). If left untreated it will lead to death in a short period of time.
- Lung cancer is a malignancy of the lung tissue. The genetic material of the lung cells become mutated and replicate excessively while invading healthy lung tissue. Sometimes the cancer starts elsewhere in the body and spread to the lung (metastasis). When the cancer destroys blood vessels there may be the production of bloody mucus or coughing up of overt blood.
Yellow to Green Mucus
Yellow to green mucus is common and usually indicates prolonged inflammation and pus formation. It can be seen with many of the inflammatory conditions already mentioned.
- Chronic bronchitis is an inflammatory condition is marked by a persistent productive cough that is often referred to as a smoker’s cough. The condition is mainly seen in long term cigarette smoking. There are frequent episodes of acute bronchitis. Mucus may vary in color clear or white to yellow, brown and green.
- Lung abscess may also present with green mucus if the abscess ruptures. The mucus and pus that was within the abscess is then coughed up. An abscess is a collection of pus and the body’s way of walling of bacteria that may have entered the lungs. There is usually an offensive odor as well.
- Bronchiectasis is a condition where there is abnormal widening of the airways. There is also excessive mucus production and accumulation. Normal mucus drainage is affected and microbes can then settle in the area and lead to infections.
- Sinusitis, both acute and chronic, can present with mucus of varying colors including white, yellow, green and sometimes red mucus when there is bleeding within the paranasal sinuses.
Brown to Black Mucus
Brown to black mucus may arise for varying reasons. A brown hue is usually associated with severe infections where there is copious pus production. Black mucus may be due to airborne particles in the mucus or blood that has degraded over time.
- Pneumoconiosis is a lung disease that arises with the inhalation of dust. It is often seen as an occupational lung disease. Black mucus is more common with coal worker’s pneumoconiosis.
- Tuberculosis (TB) and other pneumonias can also present with black mucus usually due to the degradation of blood. A persistent blood often with blood streaked mucus is a characteristic symptom of TB along with weight loss, fever and night sweats.
- Air pollution and the inhalation of smoke from a fire or with tobacco and marijuana may also cause the coughing up of brown to black mucus. It often resolves once exposure to the pollutants are discontinued.